HRTEM study on the ordered phases in Hg₃In₂Te ₆ crystals grown by Bridgman method

High-resolution transmission electron microscopy (HRTEM) is used to investigate Hg₃In₂Te₆ (MIT) crystals grown by the Bridgman method. The results show that at least two new ordered phases exist in the crystals. Their corresponding superstructure spots 1/3{422} and 1/6{422} are observed for the first time in defect zinc-blende crystals. The possible structural models of the two ordered phases are suggested based on HRTEM images. A mechanism is proposed to explain the formation and evolution of the two ordered phases. It is thought that the disorder-order phase transformation was not absolutely prevented during the furnace cooling process, due to the small cooling rate and the low thermal conductivity of the defect zinc-blende materials.